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United States Patent |
5,078,649
|
Leichliter
,   et al.
|
*
January 7, 1992
|
Hydraulic coupling for torsion isolator
Abstract
Torsion damping isolator assemblies (19 or 100 or 200) are disposed for
damping torsionals in a vehicle driveline. The assemblies include spiral
springs (62 or 202, 204) and a vane damper assembly (22 or 206) disposed
in parallel and immersed in automatic transmission fluid of a torque
converter housing (24). Damper assemblies (22 or 206) include first and
second relatively rotatable housing members (66, 68 or 208, 210). Housing
members (66 or 208) are connected to radially inner ends (62b or 202b,
204b) of the springs, and members (68 or 210) are connected to radially
outer ends (62a or 202a, 204a) of the springs. The housing members define
chambers which vary inversely in volume in response to flexing of the
spring assemblies by driveline torsionals. The chambers communication with
the fluid in the torque converter housing via restricted passages (86, 88
or 220f, 220g). As the chambers vary in volume, energy from the torsionals
is converted to fluid pressure in the chambers decreasing in volume.
Assemblies (19 and 100) include lugs (77a) drivingly connecting the second
member (68) to the torque housing. The lugs define valving members (77c,
77d) which close or partially close the passages associated with the
chamber decreasing in volume. Assembly (200) includes improved mounting
(228, 230) of the spring outer ends (202a, 204a) and improved mounting
(238) of the spring inner ends (202b, 204b). Damper assembly (206)
includes independent pistons (220) circumferentially held in position by
drive lugs (226) which also function as valving members in a manner
analogous to lugs (77a).
Inventors:
|
Leichliter; Wayne K. (Marshall, MI);
Shoals; David J. (Marshall, MI);
Mann; John C. (Marshall, MI);
Roscoe; Charles S. (Battle Creek, MI);
Detty; Rodney H. (Marshall, MI)
|
Assignee:
|
Eaton Corporation (Cleveland, OH)
|
[*] Notice: |
The portion of the term of this patent subsequent to January 7, 2009
has been disclaimed. |
Appl. No.:
|
503010 |
Filed:
|
April 2, 1990 |
Current U.S. Class: |
464/27; 464/58 |
Intern'l Class: |
F16D 003/80 |
Field of Search: |
464/24,25,27,57,58,60
192/106.2,106.1
|
References Cited
U.S. Patent Documents
1127154 | Feb., 1915 | Andersen et al. | 464/58.
|
1630737 | May., 1927 | Flanders | 464/24.
|
1978922 | Oct., 1934 | Wemp | 464/97.
|
3653228 | Apr., 1972 | Tiberio | 64/26.
|
4148200 | Apr., 1979 | Schallhorn et al. | 64/27.
|
4181208 | May., 1978 | Davis | 192/106.
|
4398436 | Apr., 1980 | Fisher | 74/688.
|
4576259 | May., 1984 | Bopp | 192/3.
|
4690256 | Sep., 1987 | Bopp et al. | 192/21.
|
4781653 | Nov., 1988 | Nakamura et al. | 464/58.
|
4782936 | Nov., 1988 | Bopp | 192/106.
|
4838107 | Nov., 1987 | Herrmann | 74/411.
|
4944374 | Jan., 1989 | Casse et al. | 192/3.
|
Foreign Patent Documents |
1953196 | Apr., 1970 | DE | 464/58.
|
2099091 | May., 1981 | GB.
| |
Primary Examiner: Stodola; Daniel P.
Assistant Examiner: Gayoso; Tony A.
Attorney, Agent or Firm: Rulon; P. S.
Claims
What is claimed is:
1. A hydraulic coupling comprising:
first and second relatively rotatable housing means defining an annular
chamber having radially spaced apart cylindrical surfaces and first and
second axially spaced apart end surfaces, the cylindrical surfaces and the
first surface defined by the first housing means, and circumferentially
spaced apart walls sealing fixed to the first housing means and extending
radially and axially across the annular chamber for dividing the annular
chamber into at least two independent arcuate chambers;
a piston disposed in each arcuate chamber, the pistons in sliding sealing
relation with the annular chamber surfaces and dividing each arcuate
chamber into pairs of volumes which vary inversely in volume in response
to movement of the pistons relative to the first housing means,
characterized by:
the second housing means being an annular radially extending housing member
having an axially facing surface defining the second end surface of the
annular chamber, the second end surface being in sealing relation with
adjacent axially facing ends of the pistons, the housing member being in
sliding sealing relation with portions of the first housing means and
retained against axial movement in a direction away from the first end
surface of the annular chamber by means affixed to the first housing
means, and the housing member having a set of circumferentially spaced and
axially extending through openings;
the pistons being separate members; and
drive means for circumferentially positioning and moving the pistons in
unison relative to the housing means, the drive means including a set of
drive lugs extending axially through the housing openings and drivingly
connected to the pistons.
2. The coupling of claim 1, wherein:
the first housing means includes first and second axially extending and
radially spaced annular walls respectively defining the first and second
cylindrical surface, and a radially extending wall defining the first end
surface; and
the means affixed to the first housing means being an annular flange
affixed to the first annular wall by fasteners and having a radially inner
portion cooperating with the housing member for the axial retaining
thereof.
3. The coupling of claim 2, further including at least two springs and
means for attaching one end of each spring to the first housing means, the
attaching
first circumferentially spaced apart portions extending radially outward
from the first annular wall of the first housing means; and
second circumferentially spaced apart portions extending radially outward
from the annular flange and in axially spaced alignment with the first
portions, and the one end or, spring disposed between one of each aligned
first and second portions and secured thereto for free radially outward
pivotal movement.
4. The coupling of claim 3, wherein the springs are nested spiral wound
springs, the one end of each spring being a radially inner end, and each
spring having a radially outer end; further including:
a first drive having a radially outer portion secured to the spring outer
ends by means restricting pivotal movement of outer ends, having a
radially intermediate portion affixed to the drive means circumferentially
positioning the pistons, and a radially inner portion including an axial
extending portion having outer cylindrical surface for journaling thereon
an inner cylindrical surface of the first housing means.
5. The coupling of claim 4, wherein each of the pistons includes an axially
extending bore loosely receiving one of the drive means lugs.
6. The coupling of claim 5, wherein:
the coupling is disposed in a torque converter housing filled with
incompressible fluid;
each of the pistons includes passage means communicating each of the
associated variable volumes with the incompressible fluid in the torque
converter housing via the axially extending bore in each piston; and
each drive lug operative to close the passage associated with the variable
volume decreasing in volume.
7. A hydraulic coupling comprising:
first and second relatively rotatable housing means defining an annular
chamber having radially spaced apart cylindrical surfaces and first and
second axially spaced apart end surfaces, the cylindrical surfaces and the
first surface defined by the first housing means, and circumferentially
spaced apart walls sealing fixed to the first housing means and extending
radially and axially across the annular chamber for dividing the annular
chamber into at least two independent arcuate chambers;
a piston disposed in each arcuate chamber, each piston having
circumferentially spaced apart surfaces and a first axially facing end
surface respectively in sliding sealing relation with the cylindrical
surfaces and the first end surface of the annular chamber, each piston
dividing the associated arcuate chamber into pairs of volumes which vary
inversely in volume in response to movement of the pistons relative to the
first housing means, characterized by:
each piston being separate members and each having a second axially facing
end surface;
the second housing means being an annular radially extending housing member
having an axially facing surface defining the second end surface of the
annular chamber, the second end surface being in sliding, sealing relation
with the second axially facing end surface of each piston, the housing
member being in sliding sealing relation with portions of the first
housing means and retained against axial movement in a direction away from
the first end surface of the annular chamber by means affixed to the first
housing means, and the housing member having a set of circumferentially
spaced and axially extending through openings; and
drive means for circumferentially positioning and moving each piston in
unison relative to the housing means, the drive means including a set of
drive lugs extending axially through the housing openings and drivingly
connected to each piston.
8. The coupling of claim 7, wherein;
the first housing means includes first and second axially extending and
radially spaced annular walls respectively defining the first and second
cylindrical surfaces and a radially extending wall defining the first end
surface; and
the means affixed to the first housing means being an annular flange
affixed to the first annular wall by fasteners and having a radially inner
portion cooperating with the housing member for the axial retaining
thereof.
9. The coupling of claim 8, further including at least two springs and
means for attaching one end of each spring to the first housing means, the
attaching means including:
first circumferentially spaced apart portions extending radially outward
from the first annular wall of the first housing means; and
second circumferentially spaced apart portions extending radially outward
from the annular flange and in axially spaced alignment with the first
portions, and the one end of each spring disposed between each aligned
first and second portions and secured thereto for free radially outward
pivotal movement.
10. The coupling of claim 9, wherein the springs are nested spiral wound
springs, the one end of each spring being a radially inner end, and each
spring having a radially outer end; further including:
a first drive having a radially outer portion secured to the spring outer
ends by means restricting pivotal movement of outer ends, having a
radially intermediate portion affixed to the drive means circumferentially
positioning each piston, and a radially inner portion including an axially
extending portion having outer cylindrical surface for journaling thereon
an inner cylindrical surface of the first housing means.
11. The coupling of claim 10, wherein each piston includes an axially
extending bore loosely receiving one of the drive means lugs.
12. The coupling of claim 11, wherein:
the coupling is disposed in a torque converter housing filled with
incompressible fluid;
each piston includes passage means communicating each of the associated
variable volumes with the incompressible fluid in the torque converter
housing via the axially extending bore in each piston; and
each drive lug operative to close the passage associated with the variable
volume decreasing in volume.
Description
BACKGROUND OF THE INVENTION
This invention relates to driveline torsion isolator mechanisms operable
over the entire operational range of a driveline. More specifically, the
invention relates to such mechanisms for vehicle drivelines.
It is well-known that the speed of an Otto or Diesel cycle engine output or
crankshaft varies even during so-called steady-state operation of the
engine, i.e., the shaft continuously accelerates and decelerates about the
average speed of the shaft. The accelerations and decelerations are, of
course for the most part, a result of power pulses from the engine
cylinders. The pulses may be of uniform frequency and amplitude when
cylinder charge density, air/fuel ratio, and ignition are uniform.
However, such uniformity does not always occur, thereby producing pulses
which vary substantially in frequency and amplitude. Whether uniform or
not, the pulses, which are herein referred to as torsionals, are
transmitted through vehicle drivelines and to passengers in vehicles. The
torsionals, which manifest themselves as vibrations, are detrimental to
drivelines and derogate passenger-ride quality. Further, when an engine is
abruptly accelerated and/or decelerated by accelerator pedal movement or
other factors, torque pulses ring through the driveline and also derogate
ride quality, such pulses are herein also referred to as torsionals.
Since the inception of the automobile, many torsion damping devices or
schemes have been proposed and used to isolate and dampen driveline
torsionals. For example, master clutches, used in combination with
mechanical transmissions, have long employed springs and secondary
mechanical friction devices to respectively isolate and dampen torsionals.
Typically, torsionals are isolated or absorbed by a plurality of
circumferentially spaced, coil springs disposed in parallel with each
other between the master clutch primary friction input and splined output.
Damping is provided by secondary mechanical friction surfaces disposed in
parallel with the springs and biased together with a predetermined force.
Damping occurs when the amplitude of the torsionals exceeds the breakaway
or slip torque of the secondary friction surfaces. With this arrangement,
portions of the torsionals less than the slip torque of the secondary
friction surfaces are transmitted directly through the clutch without
flexing or isolation by the springs, i.e., the arrangement provides
neither torsion isolation nor damping. If the slip torque of the secondary
friction surfaces is reduced by design or wear of the secondary surfaces,
damping is reduced. Further, any portions of the torsionals greater than
the spring energy absorption or storage capacity are also transmitted
directly through the clutch. If the spring rate is increased to prevent
spring collapse, the springs transmit lesser amplitude torsionals directly
through with little or no effective isolation or absorption of the
torsionals.
To increase the operational spring range and storage capacity of a torsion
damping assembly, Wemp in U.S. Pat. No. 1,978,922, proposed using a low
spring rate torsion sleeve capable of flexing substantially more than the
coil springs used with master clutches. This arrangement, like the master
clutch arrangement, also employs secondary mechanical friction surfaces
disposed in parallel and biased together with a predetermined force to
provide damping. Hence, the Wemp arrangement also fails to provide
isolation and damping of torsionals below the slip or breakaway torque of
the secondary friction surfaces. The Wemp arrangement is also underdamped
if the slip or breakaway torque of the secondary friction surfaces is
reduced.
It is known to dampen driveline torsionals with a vane damper as may be
seen by reference to U.S. Pat. No. 4,690,256 to Bopp et al and
incorporated herein by reference. In U.S. Pat. No. 4,690,256 there is
disclosed a torsion damping isolator assembly immersed in the oil of a
torque converter housing. The assembly includes resilient means for
transmitting driveline torque between input and output drives, and an
expandable chamber mechanism connected in parallel with the resilient
means. The resilient means are of the long travel type allowing about
fifty rotational degrees of travel between the input and output drives.
The mechanism, which is also of the long travel type, includes first and
second relatively movable members connected to opposite ends of the
resilient means and defining at least two chambers which vary inversely in
volume in response to flexing of the resilient means and which are in
communication with the torque converter oil via restricted passages. The
restricted passages provide inflow or charging of the volumes with torque
converter oil to prevent cavitation and control damping by restricting the
rate of outflow of oil from the volumes.
The long travel resilient and expandable chamber mechanism of U.S. Pat. No.
4,690,256 has proven to be an excellent torsion damping assembly. However,
problems have arisen with respect to life of the long travel resilient
means, with respect to control of oil flow to and from the volumes of the
expandable chamber mechanism for respectively preventing cavitation of the
expanding volumes and for ensuring sufficient oil pressure building up in
the contracting volumes, and with respect to manufacture of the mechanism
at a low cost with necessary accuracy.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a torsion damping assembly
which is effective to isolate and dampen driveline torsionals over
substantially the entire operational range of the driveline and which
employs fluid pressure to dampen the driveline torsionals.
Another object of the present invention is to provide such an assembly
immersed in automatic transmission fluid in a torque converter housing of
an automatic transmission and employing the automatic transmission fluid
to damp the driveline torsionals.
According to a feature of the invention, a hydraulic coupling comprises
first and second relatively rotatable housing means defining an annular
chamber having radially spaced apart cylindrical surfaces and first and
second axially spaced apart end surfaces, the cylindrical surfaces and the
first surface defined by the first housing means, and circumferentially
spaced apart walls sealing fixed to the first housing means and extending
radially and axially across the annular chamber for dividing the annular
chamber into at least two independent arcuate chambers; a piston disposed
in each arcuate chamber, the pistons in sliding sealing relation with the
chamber surfaces and dividing each arcuate chamber into pairs of volumes
which vary inversely in volume in response to movement of the pistons
relative to the first housing means.
The invention characterized by:
the second housing means being an annular radially extending housing member
having an axially facing surface defining the second end surface of the
annular chamber, the second end surface being in sealing relation with
adjacent axially facing ends of the circumferentially spaced apart walls
and of the pistons, the housing member being in sliding sealing relation
with portions of the first housing means and retained against axial
movement in a direction away from the first end surface of the annular
chamber by means affixed to the first housing means, and the housing
member having a set of circumferentially spaced and axially extending
through openings;
the pistons being separate members; and
drive means for circumferentially positioning and moving the pistons in
unison relative to the housing means, the drive means including a set of
drive lugs extending axially through the housing openings and drivingly
connected to the pistons.
BRIEF DESCRIPTION OF THE DRAWINGS
The torsion damping assembly of the present invention is shown in the
accompanying drawings in which:
FIG. 1 is a schematic view of a portion of a motor vehicle driveline
including the torsion damping assembly of the present invention;
FIG. 2 is a partial, detailed, sectional view of the transmission of FIG. 1
with the torsion damping assembly also shown in detail;
FIG. 3 is a partial, elevational view of the torsion damping assembly in
relief and looking along line 3--3 of FIG. 2;
FIG. 4 is a partial, sectional view of a vane damper in the torsion damping
assembly looking along line 4--4 of FIG. 2;
FIG. 5 is a graph schematically illustrating the spring rate
characteristics of the torsion damping assembly in FIGS. 1-4; and
FIG. 6 is a chart showing clutch and brake engagement for shifting the
transmission of FIG. 1;
FIG. 7 is a modified embodiment of the torsion damping assembly.
FIGS. 8-11 illustrate another modified embodiment of the torsion damping
assembly according to the invention of this application. FIG. 8 is a
staggered sectional view looking along line 8--8 in FIG. 9. FIG. 9 is an
elevational view looking in the direction of arrow 9 in FIG. 8. FIG. 10 is
a sectional view of the vane damper looking along line 10--10 in FIG. 8.
DETAILED DESCRIPTION OF THE DRAWINGS
The motor vehicle driveline, seen schematically in FIG. 1, includes an
internal combustion engine 10 and an automatic transmission 12 having an
output drive or gear 14 for driving a load such as unshown rear and/or
front wheels of a vehicle.
The transmission 12 comprises a hydrokinetic fluid coupling or torque
converter assembly 16, a ratio section 18, and a torsion damping isolator
assembly 19 including a spring assembly 20 and a vane damper assembly 22.
Components 16-22 are substantially symmetrical about a rotational axis
defined by a shaft 21 of the transmission and are shown only above the
axis for simplicity and brevity.
Torque converter assembly 16 is disposed within a torque converter housing
24 rotationally driven by an input drive 26 connected directly to a
crankshaft 28 of the engine in any of several well-known manners.
Converter assembly 16 may be of any well-known type and includes an
impeller 30 driven by housing 24, a turbine 32 driven hydrokinetically by
the impeller, and a stator 34 connectable by a one-way roller clutch 36 to
a ground such as a non-rotatable portion of the transmission housing
represented by phantom lines 37. Torque converter housing 24 is filled
with an incompressible fluid or transmission oil which is commonly
referred to as automatic transmission fluid (ATF), which lubricates the
ratio section 18, and which is often pressurized in the torque converter
housing 24.
Transmission 12 is a modified form of the generally known class of split
input torque transmissions disclosed in U.S. Pat. No. 4,398,436 and
published British Patent Application No. 2,099,091A, both of which are
incorporated herein by reference. Ratio section 18 comprises a planetary
gear set 38 controlled by friction clutches C-1 and C-2, one-way clutch
OWC-1, and brakes B-1 and B-2 to provide a reverse and three forward speed
ratio modes of operation. Planetary gear set 38 includes a first sun gear
40, first and second sets of planetary gears 42,44 supported by a common
planet carrier 46, a ring gear 48, and a second sun gear 50. Sun gear 40
is connectable to a first quill or torque converter driven shaft 52 via
clutch C-1 or clutch OWC-1. Shaft 52 is in turn connected to turbine 32
via a radially extending member 53. The first and second sets of planetary
gears are respectively in constant mesh with each other, with sun gears 40
and 50, and with ring gear 48. Planetary carrier 46 is in constant or
direct driving relation with output gear 14. Ring gear 48 is connectable
to ground via brake B-1 or to a second quill shaft 54 via clutch C-2.
Shaft 54 is connected at its left end to the vane damper 22 and at its
right end to clutch C-2 via a radially extending flange or spider 58. Sun
gear 50 is in constant mesh with planetary gears 42 and is connected to
ground via brake B-2. Ratio section 18 further includes an oil pump 60
driven by shaft 21 for pressurizing the ATF.
Looking now at the schematic representation of the torsion damping assembly
19 in FIG. 1 and in the more detailed illustration in FIGS. 2-4, assembly
19 is disposed within an annular compartment 24a defined by torque
converter housing 24. Assembly 19 is immersed within the pressurized oil
in compartment 24a. Spring assembly 20 includes two interdigitated or
nested, flat, spiral wound torsion springs 62 flexible over a range of
about fifty rotational degrees. Other types of springs may be used.
However, such springs are preferably of the long travel type. Vane damper
assembly 22 includes an annular housing assembly 64 having first and
second relatively rotatable housing members 66,68.
Springs 62 are pivotally fixed at their radially outer ends 62a to torque
converter housing 24 by pins 70 disposed 180 degrees apart; only one end
62a and one pin 70 are shown in the drawings. Radially inner ends 62b of
springs 62 are drivingly connected or hooked to an annular bracket 72.
Alternatively, spring end 62a may be connected as disclosed in U.S. Pat.
No. 4,782,936 which is incorporated herein by reference. Bracket 72
includes a cylindrical or axially extending leg 72a, a radially extending
leg 72b, and a pair of scroll-like flanges 72c extending axially from leg
72b. The scroll-like flanges are visible only in FIG. 3. Ends 62b of
spring 62 hook over ends 72d of flanges 72c to effect the driving
connection therebetween. Flanges 72c also radially support springs 62.
Member 66 includes axially extending cylindrical wall portions 66a,66b and
a radially extending annular wall portion 66c. Member 68 includes a
radially extending annular wall disposed within the cylindrical walls
66a,66b and retained therein by an annular thrust member 74 and a snap
ring 76. The interface 68a,74a of housing member 68 and thrust member 74
may be a bearing-like surface to minimize friction. However, the
interface, preferably, frictionally interacts to provide a secondary
torsion damping which increases in magnitude with increasing driveline
torsionals, as explained in further detail herein after. Member 68 is
drivingly connected to torque converter housing 24, in a manner explained
further herein after, via a pair of lugs 77a extending axially from a
bracket 77 welded at 77b to housing 24. Bracket 77 also includes a
hexagonal opening 77e at its center which receives a hexagonal end 21a of
pump shaft 21. Members 66,68 define an annular compartment 78 containing
oil from or of the type in torque converter compartment 24a. Compartment
78 is preferably sealed by seals 79 retained in grooves in member 68. As
may be seen in FIG. 4, damper compartment 78 is divided into pairs of
variable volume chambers 78a,78b by pairs of partitions or vanes 80,68c
which respectively extend radially across the compartment. Vanes 80 are
fixed to member 66 via axially extending grooves 66d,66e in the
cylindrically inner and outer surfaces of cylinder walls 66a,66b. Vanes
68c are integrally formed with member 68 and extend axially therefrom into
compartment 78. Adjacent relatively movable surfaces of the housing
members and vanes are in sliding sealing relation to minimize and control
fluid flow between the variable volume chambers. Housing member 66 is
connected directly to external splines on quill shaft 54 via mating
internal splines on cylindrical wall 66b. Housing member 66 and bracket 72
are drivingly interconnected for limited relative rotation via external
splines 66f on cylindrical wall 66 and internal splines 72e on cylindrical
leg 72a of the bracket. Bracket 72 is also connected to the outer race of
a one-way clutch OWC-2 by a radially extending portion 82 of the race. The
inner race of OWC-2 is fixed to turbine 32 and quill shaft 52. Splines
66f,72e are circumferentially biased apart by a pair of helical
compression springs 84 disposed in pairs of recesses 66g,72f respectively
defined by member 66 and bracket 72.
Springs 62 and 84 provide torsion damping assembly 19 with two spring rates
as schematically illustrated in FIG. 5. Springs 84 provide a relatively
low spring rate represented by low slope curve A when the driveline torque
is below a predetermined amount and a substantially greater spring rate
represented by higher slope curves B when the driveline torque is above
the predetermined amount.
Member 68 includes a pair of outwardly opening, arcuate recesses 68d formed
in vanes 68c and having ends defined by surfaces of radially extending
wall portions 68e,68f. Restricted passages or orifices 86,88 in wall
portions 68e,68f respectively communicate variable volume chambers 78a,78b
with the pressurized oil in torque converter compartment 24a via recesses
68d. Lugs 77a of bracket 77 extend into recesses 68d for drivingly
connecting member 68 to torque converter housing 24. The 20 lugs each
include oppositely facing, radially extending surfaces or valving members
77c,77d circumferentially spaced a predetermined number or rotational
degrees from the mutually facing surfaces of wall portion 68e,68f and
aligned with the associated restricted passages.
The valving members 77c,77d move into positions for closing or partially
closing the passages associated with the variable volume chambers which,
at any given time, are decreasing in volume, and which move away from the
passages associated with the chambers increasing in volume. The amount of
free play provided by the circumferential spacing between wall portions
68e,68f and valving members 77c,77d is preferably, but not limited to, an
amount necessary to provide unrestricted flow of oil around the associated
valving members, e.g., oil flow around valving members 77c when valving
members 77d are embodiment disclosed herein, a total free play two to four
rotational degrees is adequate. Alternatively, the free play may be
one-quarter to one-third the diameter of the passages.
During an operational mode when the direction of torque is such that
valving surfaces 77c move away from wall portions 68e and valving members
77d move into or toward contact with wall portions 68f, passages 86 are
fully open and passages 88 are closed or partially closed. During such an
operational mode, chamber 78a tends to increase or expand in volume and
torque converter oil flows relatively freely thereto to prevent
cavitation, and chamber 78b tends to decrease in volume and oil flow
therefrom is either prevented or restricted enough to significantly effect
a pressure rise therein which increases damping.
Operation of transmission 12 is in accordance with the FIG. 6 chart showing
clutch and brake engagements to effect the reverse and forward speed ratio
modes of operation. In first and reverse, 100% of driveline torque is
transmitted to the ratio section via the torque converter (T/C). In second
and third, 100% of the driveline torque is transmitted via torsion spring
assembly (T/S)20. When the transmission is in third, clutch OWC-2 engages
to provide a torque reaction for sun gear 40. While the transmission is in
either second or third, driveline torsionals emanating from the engine are
isolated or attenuated by the torsion spring assembly 20 and are damped by
the shock absorbing or energy dissipating action of damper assembly 22 and
by the variable friction forces at interfaces 68a,74a of members 68,74.
For example, when torsionals cause a sudden relative rotation of first and
second housing members 66,68 such that chambers 78a decrease in volume and
chambers 78b increase in volume, the energy in the torsionals is converted
to an increase in the pressure of the oil in chambers 78a and somewhat of
a decrease in the pressure of the oil in chambers 78b. The pressure
increases are proportional to the rate of change of the torsionals and are
greater than the pressure decreases. Elastomeric balls 90 in chambers
78a,78b prevent contact of the vanes.
Looking now at the modified embodiment of FIG. 7, therein elements which
are substantially identical to elements in the previously described
figures will be identified with the same reference numerals suffixed with
a prime. The torsion damping isolator assembly 100 of FIG. 7 embraces the
principles of the damping assembly 19 but is modified to be frictionally
clutched to the torque converter housing 24' to effect bypass of the
torque converter to a shaft 104 which is normally driven by the torque
converter turbine 32' via the member 53'. The modification consists mainly
of the addition of a clutch plate 106, a cylindrical extension 108 of the
inner cylindrical wall 66b' of the damper assembly 22'. Clutch plate 106
includes a radially extending portion 106a having an axially extending hub
portion 106b at its radially inner edge and a U-like flange portion 106c
at its radially outer edge. The inner surface of hub portion 106b is in
sliding contact with an O-ring seal 109 disposed in a groove 104a of shaft
104. The U-like flange portion 106c is connected to the radially outer
ends 62a' of springs 62' by pins 70'. Clutch plate 106 includes an annular
friction lining 110 bonded thereto and frictionally engagable with a
confronting surface 111 of the torque converter housing. Clutch plate 106
includes a set of axially extending lugs 106d analogous to lugs 77a and
received by recesses 68d' in the second housing member 68'. The inner
surface of cylindrical extension 108 is slidably splined to the outer
surface of a hub portion 53a of member 53'. Clutch plate 106 divides
torque converter chambers 24a' into two chambers, a chamber 112 between
the clutch plate and the radially extending portion of the torque
converter housing, and a chamber 114 between the clutch plate and the
torque converter.
During non-bypass operation of the torque converter in FIG. 7, pressurized
transmission oil is admitted to the torque converter via chamber 112. The
oil in chamber 112 prevents frictional engagement of the friction lining
110 with surface 111. The oil thus flows radially outward in chamber 112
past lining 110 and into chamber 114 for flow to the torque converter.
When it is desired to engage torsion damping assembly 100, as, for
example, when the vehicle is operating in a higher gear ratio and above a
predetermined vehicle speed, the direction of flow of the pressurized oil
is reversed by actuation of a suitable valve, not shown. Specifically, the
pressurized oil is now admitted to chamber 114 where it acts against the
radially extending portion 106a of clutch plate 106 and slides the entire
damping assembly to the left to frictionally engage lining 110 with
surface 111. Driveline torque now bypasses the torque converter and is
transmitted to shaft 104 via the damping assembly. Since clutch plate 106
is not normally engaged when the engine is at idle, torsion damping
assembly 100 does not require driving connections which suppress idle
rattle. Hence, the loose spline connections to the outer periphery of the
housing member 66 and to housing member 68 for suppression of idle rattle
are not needed.
Looking now at FIGS. 8-11, the torsion damping isolator assembly 200
therein is functionally the same as the damping assemblies in FIGS. 2 and
7. However, assembly 200 differs structurally in several ways. As in FIGS.
2 and 7, assembly 200 includes a pair of nested, flat, spiral wound
springs 202,204, and a vane type damper mechanism 206 including housing
members 208,210 defining an annular chamber 212, and, as in FIG. 7,
assembly 200 includes a clutch plate 216. Plate 216 includes a radially
extending portion 216a having an axially extending hub portion 216b at its
center and an axially extending flange portion 216c at its radially outer
edge. An inner cylindrical surface of hub portion 216b cooperates with the
O-ring seal 109 in FIG. 7 and an outer cylindrical surface of the hub
portion provides a journal for an inner cylindrical surface of housing
member 208.
Annular chamber 212 includes radially spaced apart cylindrical surfaces
212a,212b defined by axially extending annular wall portions 208a,208b of
housing member 208, and axially spaced apart end surfaces 212c,212d
respectively defined by a radially extending portion 208c of housing
member 208 and housing member 210. Housing wall portion 208b includes a
set of internal splines 208d which slidably cooperate with splines on hub
portion 53a in FIG. 7 or directly with the splines on shaft 104. Annular
chamber 212 is divided into three arcuate chambers 217 sealed from each
other by fixed vanes or walls 218. The walls are press fit into grooves in
wall portions 208a,208b,208c, and extend radially and axially across the
annular chamber. Radially extending wall 208c is structurally strengthened
by raised bases 208e at the location of the grooves therein for walls 218.
The radially outer extent of axially extending wall 208a includes a
radially outwardly extending flange 208f and a pair of scroll shaped pad
portions 208g to reduce transverse stress concentrations in the springs
when they decrease in overall diameter due to transmission of torque in
the positive direction.
Each arcuate chamber 217 is divided into pairs of variable volume chambers
217a,217b by movable vanes or pistons 220. Pistons 220 are each separate
members. Each piston includes radially inner and outer surfaces 220a,220b
in sliding sealing relation with housing member cylindrical surfaces
212a,212b, an axially facing end surfaces 220c in sliding sealing relation
with housing end surface 212c, and an axially facing end surface 220d in
sealing relation with end surface 212d of housing member 210. Each piston
also includes a blind recess or bore 220e and restricted passages
220f,220g for communicating variable volumes 217a,217b with the
pressurized oil in torque converter compartment 24a via recesses 220e. In
FIG. 10, one of the pistons 220 is sectioned through the restricted
passages. Axial spacing of the piston end surfaces between the end
surfaces of the chamber and between surface 212d and the adjacent ends of
walls 218 is controlled and maintained by an annular shim 222 sandwiched
between housing member 210 and a radially inner portion 224a of an annular
flange 224. Flange 224 abuts the free axial end of housing wall 208a and
is affixed to housing member 208 by appropriate fasteners, such as by two
sets of three fasteners 225 which extend through openings in flange 224,
openings in pad portions 208g, and openings in flange 208f. A radially
outer portion 224b of flange 224 includes through openings 224c spaced 180
degrees apart and in axial alignment with openings 208h in flange 208f.
Housing member 210 includes inner and outer circumferential surfaces
210a,210b in sliding sealing relation with cylindrical wall surfaces
212a,212b, and three circumferentially spaced apart through openings 210c
which loosely receive round pin lugs 226 fixed at one end to clutch plate
216 and the other end received by piston recesses 220e. As in the
embodiment of FIGS. 2 and 7, the lugs function as valving members to
control torque converter oil flow into and out of the variable volume
chambers. Further, since pistons 220 are separate members, lugs 226
position and fix the circumferential spacing of the pistons such that the
valving relation of each lug is always in proper relation with the
associated restricted passage even if the circumferential spacing of the
lugs on plate varies during manufacture. Still further, since lugs 226 are
loosely received by housing member openings 210c and piston recesses 220e,
pistons surfaces 220d are free to slide a limited amount relative to
housing member surface 212d.
Housing member 208 and pistons 220 may be made of any suitable material and
may be formed by any of several well known processes. Herein, they are
preferably formed of powered metal and surfaces thereof, which form
sliding sealing relation with each other, may be ground.
Springs 202,204 respectively include radially outer ends 202a,204a and
radially inner ends 202b,204b. The ends are attached in a manner to reduce
stress concentrations and improve life. Outer ends 202a,204a are secured
to the radially outer extent of clutch plate 216 by pins 228 and brackets
230. Pins 228 transmit torque between the clutch plate and the springs and
brackets 230 support the outer spring ends in cantilever fashion (i.e.,
prevents free pivotal movement of ends 202a, 204a) to improve stress
distribution in the springs as they wind up or contract radially inward
while transmitting torque in the positive direction. Brackets 230 have a
somewhat J-shaped cross section, as shown in FIG. 8. The brackets are
welded to plate 216 at 232,234 and provide a pocket which axially and
radially confines spring end movement. The axially extending and radially
inward lag 230a of each bracket follows the scroll curvature of the
springs. Pins 228 are received in axially aligned bores 230b,230c in
radially extending lags of the brackets and in bores in the spring ends.
Each pin is locked in place by a weld 236. The inner ends 202b,204b of the
springs are secured to housing member 208 by pins 238 extending through
axially aligned openings 208h,224c and received in a bore in each spring
end. When the springs are transmitting positive torque and tending to wind
up, pivotal movement of the spring ends 202b,204b is limited by scroll
pads 208g. When the springs are transmitting negative torque and tending
to unwind or expand radially, pins 238 allow free pivotal movement of the
spring ends.
While the embodiments of the present invention have been illustrated and
described in detail, it will be apparent that various changes and
modifications may be made in the disclosed embodiments without departing
from the scope or spirit of the invention. The appended claims are
intended to cover these and other modifications believed to be within the
spirit of the invention.
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